As mentioned above, it's definitely always been been like this, but as I don't don't get that many incoming calls, and because I reboot quite often when fiddling with stuff, it took me a while to spot what was going on, sorry.

I've tried tweaking lots of pulseaudio settings, but haven't been able to influence this in any way. I also had the idea of killing and restarting pulseaudio after answering a call, to see if I could bring back audio during the call itself, but unfortunately, it only seems to work after the call has finished.

It occured to me that testing it might end up costing you money in calls, so if you ever wanted a donation, I'd be more than happy to oblige. No offence intended if you don't go in for that kind of thing - just thought I'd offer.

Or if there's any crazy alternatives like trying to use an alternative phone app (Android via AD or other Linux via chroot?), I'd be more than happy to give it a go if you thought it was even feasible.

Many thanks